The NBA doesn’t need to work with the BIG3, but barring players and referees from participating (when they already participate with other events/leagues) seems like a step too far.
I don’t think the NBA allows any of its players to take player contracts in any other leagues.
Usually when they play in other events, it’s representing their country, charity events, or for personal fun. It’s not for pay from a competing league.
You could also argue that it is beneficial for the NBA to work with the BIG3, either in helping to increase the popularity of basketball in general, as a development option, or as a semi-retirement option for guys who can still hoop but can’t handle the full grind.
I’d say that Ice Cube’s public persona since he first presented BIG3 has been enough for the NBA to stay way.
The NBA wants control and they can’t control BIG3. I don’t know if the BIG3 doesn’t much to expand basketball’s popularity in a way it helps the NBA. If anything, the BIG3’s who business model is to ride the NBA’s coattails and try to force the NBA to pretend as if the BIG3 is a sanctioned partner.
The BIG3 is trying to expand, using the NBA’s brand and prestige to their own benefit but it doesn’t help the NBA at all other than filling dates in NBA franchise controlled arenas in the summer.
And they have a celebrity CEO who can generate publicity.